02 — Rough & specimen
Rough & Specimen
Uncut crystals, matrix plates and trapiche emerald for collectors, lapidaries and mineral cabinets.
| Piece | Origin | Weight | Size | Price |
|---|---|---|---|---|
| Hexagonal crystal in calcite | Muzo | 14.2 g | 31 mm | $180 |
| Trapiche slice, polished | Muzo | 1.84 ct | 9 mm | $460 |
| Matrix plate, twin crystals | Coscuez | 62 g | 74 mm | $540 |
| Terminated prism, gem-grade | Chivor | 6.1 g | 22 mm | $1,150 |
| Collector’s lot, 9 pieces | Mixed Boyacá | 41 g | — | $295 |
| Pyrite-bearing matrix | La Pita | 88 g | 91 mm | $410 |
Rough material is graded differently from cut stones — there is no oil grade on an uncut crystal. If you are moving from specimens to gems, start with loose cut stones and how we grade and disclose them.
Three different buyers
Rough is not one market — it is three, and they want opposite things
The single most common mistake in buying rough is not knowing which of these you are. A stone that is excellent for one is a poor buy for another, and the price you should pay differs sharply.
| Buyer | What they want | What they will pay for |
|---|---|---|
| The cutter | Clean interior volume and a shape that yields a good finished stone. | Predicted yield. Crystal beauty is irrelevant — they are going to destroy it. An ugly, scuffed crystal with a clean heart beats a handsome one full of fractures. |
| The specimen collector | Crystal form: sharp hexagonal faces, an intact natural termination, and ideally the host rock still attached. | Form and aesthetics. A collector will pay a large premium for a crystal in matrix that a cutter would value at scrap, because cutting it destroys what makes it worth money. |
| The carver | Mass, workable texture and interesting colour zoning. | Volume and character rather than clarity. Inclusions that would ruin a faceted stone are often acceptable or even desirable. |
Tell us which one you are before we quote. We would rather sell you the right stone at a lower price than the wrong stone at a higher one — a cutter who buys a collector specimen has overpaid badly, and a collector who buys cutting rough has bought something plain.
The honest warning
Nobody can reliably tell you the yield — including us
This is the fact the rough trade is built on and the one most sellers skate past. An emerald crystal’s interior is largely hidden. Surface-reaching fractures can be traced, and immersion and strong light reveal something, but the fractures and inclusions that decide whether a 10-carat crystal produces a fine 2-carat stone or four disappointing melee stones are frequently invisible until the saw is already through it.
That uncertainty is precisely why rough is cheaper per carat than cut material. You are not getting a discount — you are being paid to accept the risk the cutter would otherwise carry. Emerald yields are low and variable even in experienced hands, and a bad crystal can yield nothing usable at all.
So: if you cannot afford to lose the purchase price, do not buy rough. Buy a cut stone where what you see is what you own. Anyone promising you a specific yield from an uncut emerald is either guessing or lying, and we will not do either — we will tell you what we can see and name what we cannot.
Vocabulary
What the terms on a specimen listing mean
- Hexagonal prism — emerald’s natural crystal habit. Beryl grows as a six-sided column. A well-formed prism is the baseline of a good specimen.
- Termination — the natural flat face capping the crystal. Terminated means it is intact rather than broken off. It matters a great deal to collectors and not at all to cutters.
- Matrix — the host rock the crystal grew in. In Colombia that is typically white calcite veining through dark carbonaceous shale, and the contrast of green crystal against it is a large part of a specimen’s appeal.
- Doubly terminated — intact natural faces at both ends, meaning the crystal grew freely rather than out of a wall. Uncommon and priced for it.
- Gem rough versus specimen — the same stone described for two different buyers. We label which we think it is and say why.
- Contact — a surface where the crystal was attached or broken. Reduces specimen value; usually irrelevant to a cutter.
Questions
Buying rough and specimens
Can you tell me how many carats I will get out of it?
We will tell you the rough weight, the fractures we can trace, what immersion shows and what a reasonable cutter might attempt. We will not give you a yield figure, because it would be a guess dressed up as a fact. If a seller gives you a confident yield number on an uncut emerald, treat that as information about the seller.
Is rough emerald treated?
Rough is normally sold untreated — oiling is done after cutting, because the point of filler is to reduce the visibility of surface-reaching fractures in a finished stone. That is one genuine advantage of buying rough: what you are looking at is the actual material. It also means nothing is hiding the fractures, so look harder.
Is rough cheaper than cut, overall?
Per carat of rough, yes, substantially. Per carat of finished stone you end up with, often no — once you account for yield loss and the cutter’s fee, rough bought at retail frequently works out level with or worse than simply buying the cut stone. Rough makes sense when you want the crystal itself, when you are cutting it yourself, or when you are buying at genuine volume and can average the risk across many stones.
Do specimens come with the matrix attached?
When the specimen has one, yes, and we will not remove it — stripping matrix off a good Colombian crystal destroys value. Every listing says whether the stone is in matrix, free-standing, or a fragment, because the three are priced very differently.
Going deeper: the full guide to buying rough emerald. Prefer a finished stone where what you see is what you own? Loose cut stones.